1. Field of the Invention
The present invention relates to a crosstalk elimination method and system for use in a transmission system that transmits a plurality of pairs of a data signal and a clock signal thereof.
2. Description of the Related Art
In the case of a plurality of transmission lines that are close together, crosstalk occurs when magnetic fields or current from nearby transmission lines interrupt electrical currents in a transmission line. Since crosstalk causes data error and transmission error, it is very important to effectively eliminate crosstalk from the transmission system.
A simple but effective crosstalk elimination method is to transmit a plurality of pairs of data and clock signals through different cables. Since the pairs of data and clock signals are properly separated from each other, such a conventional system effectively eliminates crosstalk even In the case where these data signals are not synchronized.
However, the conventional transmission system needs as many cables as the pairs of data and clock signals. Therefore, laying cables should be done with caution not to generate crosstalk, resulting in a difficult pattern design. Further, it is difficult to downsize transmission equipment in the event a large number of pairs of data and clock signals are to be transmitted.
An object of the present invention is to provide a crosstalk elimination method and system that reduces number of cables and permits downsizing of transmission equipment.
Another object of the present invention is to provide crosstalk elimination method and system allowing a stable and reliable transmission system with simplified cabling.
According to the present invention, in a system for eliminating crosstalk among a plurality of data signals traveling from sending equipment to receiving equipment through a transmission cable, clock signals and their associated data signals are not synchronized with each other.
The sending equipment includes a detector for detecting a possible crosstalk timing in each of the data signals by comparing phases of the clock signals to transmit it to the receiving equipment. The receiving equipment includes a read timing shifter for shifting a read timing of each of the clock signals associated with a corresponding data signal to a no-crosstalk timing determined based on the possible crosstalk timing.
The detector may include: a leading edge detestor for detecting a leading edge timing of each of the clock signals; a trailing edge detector for detecting a trailing edge timing of the clock signal; and a crosstalk timing detector for detecting the possible crosstalk timing in a corresponding data signal based on the trailing edge timing of the clock signal associated with it and leading edge timings of all clock signals other than the clock signal.
The receiving equipment may further include: a first data reading section for reading each of the data signals received from the sending equipment according to the no-crosstalk timing to produce a first data signal; and a second data reading section for reading the first data signal according to the read timing of a corresponding clock signal.
As an embodiment of the present invention, the sending equipment may include a phase comparator for comparing phases of the clock signals to produce a phase shift trigger signal indicating a possible crosstalk timing for each of the data signals, to transmit the phase shift trigger signal to the receiving equipment. The receiving equipment may include: a read timing shifter for receiving the phase shift trigger signal and a corresponding clock signal and shifting a read timing of the corresponding clock signal depending on the phase shift trigger signal to produce a shifted read timing signal: and a data reading section for receiving the data signal, the corresponding clock signal, and the shifted read timing signal, and reading the data signal according to the shifter read timing signal to produce a first data signal and thereafter reading the first data signal according to the corresponding clock signal to produce a final data signal.
The phase comparator may include: a leading edge detector for detecting a leading edge timing of each of the clock signals; a trailing edge detector for detecting a trailing edge timing of the clock signal; a crosstalk timing detector for detecting the possible crosstalk timing in a corresponding data signal based on the trailing edge timing of the clock signal associated with it and leading edge timings of all clock signals other than the clock signal; and a trigger generator for generating the phase shift trigger signal from the possible crosstalk timing, wherein the phase shift trigger signal has a pulse width having the possible crosstalk timing located therein.
The read timing shifter may include a selector for selecting one of the corresponding clock signal and a fixed signal being a logic high level depending on the phase shift trigger signal, wherein the corresponding clock signal is selected when the phase shift trigger signal is a logic low level and the fixed signal is selected when the phase shift trigger Signal is a logic high level.
The data reading section may include a first flip-flop circuit for reading the data signal according to the shifted read timing signal to produce the first data signal; and a second flip-flop circuit for reading the first data signal according to the corresponding clock signal.
As described above, according to the present invention, crosstalk among a plurality of data signals can be effectively removed. Therefore, a reliable and stable transmission system can be achieved. Further, the plurality of data signals can be transmitted as a bundle through a single cable, resulting in the reduced number of cables and a downsizing of the transmission system. This causes the design of cabling to be simplified and its cost to be reduced.